This application relates generally to a writing/drawing tablet. More specifically, this application relates to utilizing a pressure sensitive display in combination with a touch screen that can capture image data from the image being drawn on the pressure sensitive display and share the image via wireless connectivity.
In general, Bistable Liquid Crystal Displays (BLCD), and in particular, Cholesteric Liquid Crystal Displays (ChLCDs), have proven to have great potential to create low cost pressure sensitive displays that are efficient power consumers and that can be utilized in a number of unique devices. These displays use a pressure sensitive feature of the ChLCDs that allows generating an image using pressure but consuming little or no power to do so, and requiring no power to maintain the image on the display for extended periods.
Recently, the Boogie Board® pressure sensitive cholesteric liquid crystal writing tablet, of Improv Electronics® has appeared on the market in which a pointed stylus or a finger of a user can be used to write or trace an image on the surface of the tablet. (Improv Electronics® is a unit of Kent Displays, Inc.) Such a stylus does not transfer any ink or other material to any surface. This tablet offers a considerable improvement over previous tablet technologies in that the image can be simply and instantly erased with the push of a button that applies a voltage pulse to electrodes in the tablet. In a cholesteric liquid crystal tablet, the liquid crystal is sandwiched between two substrates that are spaced to a particular gap. The upper substrate is flexible and the bottom substrate is painted with a light absorbing (black or colored) background. The cell gap is usually set by plastic or glass spacers that are either cylindrical or spherical in shape. When one presses on the top substrate with a point stylus or finger or nail tip or other object, the liquid crystal is locally displaced. Flow induced in the liquid crystal changes its optical texture from a transparent to a brilliant reflective color at the location of the pressure. The reflective lighter color contrasts well to the dark background of the lower substrate. An image traced by the stylus or finger will remain on the tablet indefinitely until erased, typically consuming no power. Erasure is accomplished by applying a voltage pulse to transparent conducting electrodes on the inner surface of the substrates that drive the cholesteric liquid crystal from its color reflective state back to its transparent state.
The above described principle is disclosed in more detail in U.S. Pat. No. 6,104,448, incorporated herein by reference. Polymer dispersions can be used to control the pressure sensitivity and resolution of the image as described in U.S. patent application Ser. No. 12/152,729, filed on May 16, 2008, and incorporated herein by reference. Other modes of operation including multiple color images and select erase are described in the patent application publication given above as well as U.S. Pat. No. 8,139,039 filed on Jul. 29, 2008, and incorporated herein by reference.
It would therefore be desirable to have a writing tablet device where an image being drawn is directly observed on the drawing pad but simultaneously (or subsequently) captured electronically and digitized so as to be observed on a computer screen or any other external device connected to the writing tablet device as well as stored for later recall and use. It would be further useful that the device be able to operate as an input device to a connected external device and that the connected external device have specialized software to allow users to enhance the image and share the image with others over the internet. Examples of external devices include smartphones, tablets, personal computers (laptops/desktops) netbooks, possible eReaders with connectivity and other devices with Bluetooth and appropriate software. The writing tablet device may contain software written for Apple iOS devices and additional software written for Android and other devices. Other features such as low-cost and low-power requirements would be of further advantage.